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51.
Mark E. Mitchell Stephen F. Matter Richard D. Durtsche Ishi Buffam 《Urban Ecosystems》2017,20(5):1121-1133
Green roofs are emerging engineered ecosystems that provide multiple benefits, but many are constructed with nutrient-rich substrate and have been found to leach out high levels of phosphorus (P) in runoff. It is unclear, however, how long green roofs act as sources of P or what mechanisms are responsible for these net losses. We measured P concentrations in runoff water over 4 years from a 1–5 year old extensive green roof in Cincinnati, OH, USA, produced a model to predict runoff P levels into the future, and validated predictions using runoff from 2 nearby extensive green roofs. P concentrations in runoff from the focal green roof were on par with heavily fertilized agroecosystems and displayed strong seasonal dynamics and a rapid decline over the 4-year study. Runoff measurements and changes in substrate P content over a 2-year period were used to estimate a mass balance for green roof P. P loss from the substrate was substantial (4.55 ± 2.3 g P/m2/yr), but only a small portion of the loss was attributable to leaching of P in runoff (0.19–0.65 g P/m2/yr). Missing P may be attributed to a combination of plant uptake and altered P form and binding strength, but further research is needed to precisely identify the mechanisms of P depletion. Our results also suggest that these and similar extensive green roofs are likely to act as environmentally significant sources of P for 10 or more years following roof installation, highlighting the need for reductions in initial substrate P content. 相似文献
52.
53.
Nathaniel E. Urama Emmanuel O. Nwosu Denis N. Yuni Stephen E. Aguegboh 《International migration (Geneva, Switzerland)》2017,55(1):37-50
The study analyses how remittances to Nigeria affect the labour supply of recipients using Propensity Score Matching (PSM) and a Log‐Linear regression model, with data from the 2013 Nigerian General Household Survey. The PSM results show that for the entire sample, the difference between the average amount of labour supplied per week by those that receive remittances and the amount they would have supplied without remittances is insignificant. The marginal impact analysis also shows that, ceteris paribus, the average labour supply for all recipients is inelastic to remittances. The results from the sub‐group analysis, however, show that receiving remittances negatively affects the labour supply of the self‐employed in agriculture, teenagers and the elderly. These results led us to the recommendation that policies to increase the inflow of remittances should be encouraged but in tandem with programmes to educate farmers on the benefit of investing remittances received in their farming business. 相似文献
54.
Bisexual youth are at elevated risk for depression when compared with lesbians and gay men. Research on bisexual stigma suggests that these youth are uniquely vulnerable to stress related to sexual identity disclosure. Depression associated with this stress may be buffered by social support from parents and friends. We examined the differential influence of social support from parents and friends (Child and Adolescent Social Support Scale) on the relation between disclosure stress (LGBTQ Coming Out Stress Scale) and depressive symptoms (Beck Depression Inventory) and differences by gender in a sample of cisgender bisexual youth (N = 383) using structural equation modeling. Parental support buffered the association between stressful disclosure to family and depressive symptoms, especially for bisexual men; bisexual women seemed not to benefit from such support when disclosure stress was high. This nuanced examination elucidates the ways family members and clinicians can best support bisexual youth sexual identity disclosure. 相似文献
55.
Chodziwadziwa W. Kabudula Brian Houle Mark A. Collinson Kathleen Kahn Stephen Tollman Samuel Clark 《Social indicators research》2017,133(3):1047-1073
Understanding the distribution of socioeconomic status (SES) and its temporal dynamics within a population is critical to ensure that policies and interventions adequately and equitably contribute to the well-being and life chances of all individuals. This study assesses the dynamics of SES in a typical rural South African setting over the period 2001–2013 using data on household assets from the Agincourt Health and Demographic Surveillance System. Three SES indices, an absolute index, principal component analysis index and multiple correspondence analysis index, are constructed from the household asset indicators. Relative distribution methods are then applied to the indices to assess changes over time in the distribution of SES with special focus on location and shape shifts. Results show that the proportion of households that own assets associated with greater modern wealth has substantially increased over time. In addition, relative distributions in all three indices show that the median SES index value has shifted up and the distribution has become less polarized and is converging towards the middle. However, the convergence is larger from the upper tail than from the lower tail, which suggests that the improvement in SES has been slower for poorer households. The results also show persistent ethnic differences in SES with households of former Mozambican refugees being at a disadvantage. From a methodological perspective, the study findings demonstrate the comparability of the easy-to-compute absolute index to other SES indices constructed using more advanced statistical techniques in assessing household SES. 相似文献
56.
Stephen Farrall Ben Hunter Gilly Sharpe Adam Calverley 《International Journal of Social Research Methodology》2016,19(3):287-300
Attrition represents a significant obstacle to overcome in any longitudinal research project. It is, perhaps, most keenly felt when the data collected are from a qualitative study, since, unlike quantitative longitudinal research, weighting factors cannot be applied to ‘correct’ for any biases in the achieved sample and even a small number of ‘lost’ respondents can equate to a large percentage of the original sample. It is perhaps because of qualitative longitudinal research’s (QLR) reliance on, generally speaking, smaller samples that few have been able to shed much light on which re-contacting procedures are associated with achieving higher rates of retention. In this article, using data from a fifth sweep of a larger but particularly challenging cohort of 199 former probationers, we explore the strategies which helped us maintain high levels of retention in a QLR study. The article contains many practical suggestions which others planning or undertaking similar studies may find useful. 相似文献
57.
Stephen Edgell 《The Sociological review》2012,60(4):773-775
58.
Darwin (1872) hypothesized that some facial muscle actions associated with emotion cannot be consciously inhibited, particularly when
the to-be concealed emotion is strong. The present study investigated emotional “leakage” in deceptive facial expressions
as a function of emotional intensity. Participants viewed low or high intensity disgusting, sad, frightening, and happy images,
responding to each with a 5 s videotaped genuine or deceptive expression. Each 1/30 s frame of the 1,711 expressions (256,650
frames in total) was analyzed for the presence and duration of universal expressions. Results strongly supported the inhibition
hypothesis. In general, emotional leakage lasted longer in both the upper and lower face during high-intensity masked, relative
to low-intensity, masked expressions. High intensity emotion was more difficult to conceal than low intensity emotion during
emotional neutralization, leading to a greater likelihood of emotional leakage in the upper face. The greatest and least amount
of emotional leakage occurred during fearful and happiness expressions, respectively. Untrained observers were unable to discriminate
real and false expressions above the level of chance. 相似文献
59.
Although there is strong evidence that single physical, psychosocial and organisational risk factors are each independent predictors of low back symptoms (LBS), little is known about their combination/interaction, particularly in those working in developing countries. A total of 1294 Indonesian coal mining industry workers reported information about physical, psychosocial, and organisational factors using self-reported questionnaires and were placed into one of four combination exposure groups: 1) high physical (working with bent trunk; whole body vibration exposure; lifting) and high psychosocial (high effort; low reward; work stress), 2) high physical and low psychosocial, 3) low physical and high psychosocial, and 4) low physical and low psychosocial (as the reference group). The odds of LBS in the high physical and high psychosocial group was 5.15 times (95% confidence interval 2.69-9.86) that of the reference group. Psychosocial factors played a more important role than physical factors in increasing the likelihood of reporting LBS. Permanent and night shift workers were more likely to report LBS. These findings imply that efforts to reduce LBS in this workplace should address both psychosocial and physical factors but psychosocial factors should be the priority, with a special focus on permanent and night shift workers. 相似文献
60.
Business enterprises run by youth can create jobs and teach the principles of free enterprise but also convey skills that can be used by employees in large companies, as well as political activists and entrepreneurs. Research is needed to test the efficacy of this approach and identify its key components. 相似文献